One-pot synthesis of isosorbide from cellulose or lignocellulosic biomass: a challenge?

• Isaline Bonnin,
• Raphaël Mereau,
• Thierry Tassaing and
• Karine De Oliveira Vigier

Beilstein J. Org. Chem. 2020, 16, 1713–1721, doi:10.3762/bjoc.16.143

• to isosorbide, a sustainable and interesting route should be the design of a heterogeneous catalyst composed of a metal supported on an acid support. These catalysts should be designed in order to be stable in water and tolerant to the presence of lignin. Otherwise, the solution should be to realize

Heterogeneous photocatalysis in flow chemical reactors

• Christopher G. Thomson,
• Ai-Lan Lee and
• Filipe Vilela

Beilstein J. Org. Chem. 2020, 16, 1495–1549, doi:10.3762/bjoc.16.125

• separation and recycling, HPCats show advantages such as an enhanced photostability and selectivity [47][48]. A heterogeneous catalyst with a high surface area is often associated with a greater number of surface-active sites for catalysis to occur and makes morphological control critical to the catalyst

• chemistry as previously discussed. This combines the ease of separation and recyclability of a heterogeneous catalyst, with the detailed characterisation, accessibility and synthetic versatility of a homogeneous photocatalyst. Some desirable properties of a solid support are hence; (i) a strong

The charge-assisted hydrogen-bonded organic framework (CAHOF) self-assembled from the conjugated acid of tetrakis(4-aminophenyl)methane and 2,6-naphthalenedisulfonate as a new class of recyclable Brønsted acid catalysts

• Svetlana A. Kuznetsova,
• Alexander S. Gak,
• Yulia V. Nelyubina,
• Vladimir A. Larionov,
• Han Li,
• Michael North,
• Vladimir P. Zhereb,
• Alexander F. Smol'yakov,
• Artem O. Dmitrienko,
• Michael G. Medvedev,
• Igor S. Gerasimov,
• Ashot S. Saghyan and
• Yuri N. Belokon

Beilstein J. Org. Chem. 2020, 16, 1124–1134, doi:10.3762/bjoc.16.99

• , including the ring opening of epoxides by water and alcohols. A Diels–Alder reaction between cyclopentadiene and methyl vinyl ketone was also catalyzed by F-1 in heptane. Depending on the polarity of the solvent mixture, the CAHOF F-1 could function as a purely heterogeneous catalyst or partly dissociate

• , providing some dissolved F-1 as the real catalyst. In all cases, the catalyst could easily be recovered and recycled. Keywords: Brønsted acid catalyst; charge-assisted hydrogen-bonded framework; Diels–Alder; epoxide ring opening; heterogeneous catalyst; Introduction Tremendous successes in homogeneous

• . Depending on the polarity of the solvent mixture, F-1 could function as a purely heterogeneous catalyst or as a reservoir, providing some soluble F-1 as the real catalyst. In all cases the catalyst could easily be recovered and recycled. The system has the potential for future elaboration, for example, by

A systematic review on silica-, carbon-, and magnetic materials-supported copper species as efficient heterogeneous nanocatalysts in “click” reactions

• Pezhman Shiri and
• Jasem Aboonajmi

Beilstein J. Org. Chem. 2020, 16, 551–586, doi:10.3762/bjoc.16.52

• (40) with pyridine-3,5-dicarboxylic acid (39) using P(OC₆H₅)₃ (TPP). The ligand 41 was immobilized on 3-chloropropyltrimethoxysilane (CPTMS, 43) to afford TMSP–nSiO2 (44). Material 44 was then reacted with CuBr2 in methanol at reflux for 24 h to produce the heterogeneous catalyst Cu(II)Br2–BTP@TMSP

• ) (64) (Scheme 10) [32]. An interesting aspect of the heterogeneous catalyst SNIL–Cu(II) (64) is its successful application in the [3 + 2] cyclization synthesis of “click” products under mild reaction conditions. 0.05 mol % of 64 and 2 mol % of sodium ʟ-ascorbate were used to prepare a range of

• substitutions were efficiently transformed to the corresponding products in excellent yields. To show the high efficiency of this catalytic system, bis-“click” and tris-“click” reactions were also effectively performed (Scheme 10). The heterogeneous catalyst 64 could be used for six consecutive cycles without

One-pot synthesis of substituted pyrrolo[3,4-b]pyridine-4,5-diones based on the reaction of N-(1-(4-hydroxy-6-methyl-2-oxo-2H-pyran-3-yl)-2-oxo-2-arylethyl)acetamide with amines

• Valeriya G. Melekhina,
• Andrey N. Komogortsev,
• Boris V. Lichitsky,
• Vitaly S. Mityanov,
• Artem N. Fakhrutdinov,
• Arkady A. Dudinov,
• Vasily A. Migulin,
• Yulia V. Nelyubina,
• Elizaveta K. Melnikova and
• Michail M. Krayushkin

Beilstein J. Org. Chem. 2019, 15, 2840–2846, doi:10.3762/bjoc.15.277

• -one (4), arylglyoxals 5, and acetamide (6) using SnCl2–SiO2 nanoparticles as heterogeneous catalyst under solvent-free conditions [10]. However, as we found out, the use of a catalyst was unnecessary for this transformation. In turn, refluxing the reaction mixture in acetonitrile was sufficient for

A review of asymmetric synthetic organic electrochemistry and electrocatalysis: concepts, applications, recent developments and future directions

• Munmun Ghosh,
• Valmik S. Shinde and
• Magnus Rueping

Beilstein J. Org. Chem. 2019, 15, 2710–2746, doi:10.3762/bjoc.15.264

• electrodes Electrodes with chiral surfaces have long been prepared through the adsorption of chiral active auxiliaries onto the surface of the metallic electrode. In such cases, the chiral electrode becomes an inherent part of the electrochemical cell and serves as a heterogeneous catalyst. A recent article

Recent advances on the transition-metal-catalyzed synthesis of imidazopyridines: an updated coverage

• Gagandeep Kour Reen,
• Ashok Kumar and
• Pratibha Sharma

Beilstein J. Org. Chem. 2019, 15, 1612–1704, doi:10.3762/bjoc.15.165

• the first step which was converted to the final product via radical cation intermediate 17 in the second step (Scheme 6). This additive-free approach offered an easy separation and reusability of heterogeneous catalyst along with the use of air as environmentally benign oxidant. The use of zinc and

• the use of toxic reagents and solvents, harsh reaction conditions and long reaction times. The use of a heterogeneous catalyst and water made this method a green and sustainable approach for organic transformations. This transformation involved the well known three-component reaction of 3 with 1 and 2

An overview on recent advances in the synthesis of sulfonated organic materials, sulfonated silica materials, and sulfonated carbon materials and their catalytic applications in chemical processes

• Hashem Sharghi,
• Pezhman Shiri and
• Mahdi Aberi

Beilstein J. Org. Chem. 2018, 14, 2745–2770, doi:10.3762/bjoc.14.253

• multicomponent reactions and some of them were mentioned below. Moosavi-Zare et al. immobilized 1,4-diazabicyclo[2.2.2] octanesulfonic acid chloride on SiO2 as a nanostructured heterogeneous catalyst. The silica-bonded 1,4-diazabicyclo[2.2.2]octanesulfonic acid chloride catalyst 71 was prepared in some steps as

• 80 °C using MWCNTs-SO3H composite 97 as the efficient and heterogeneous catalyst. The reaction was also performed under the same conditions using different catalysts including Fe3O4, CuFe2O4, ZnS nanoparticles, TiO2, MWCNTs, MWCNTs/H2SO4, MWCNTs–COOH, and Ph–SO3H, but the products were not achieved

β-Hydroxy sulfides and their syntheses

• Mokgethwa B. Marakalala,
• Edwin M. Mmutlane and
• Henok H. Kinfe

Beilstein J. Org. Chem. 2018, 14, 1668–1692, doi:10.3762/bjoc.14.143

• also well documented and new ones continue to be investigated. Although a number of methodologies are reported for their synthesis, there is still room for improvement in terms of finding more efficient asymmetric catalysts as well as heterogeneous catalyst systems for the hydroxysulfenylation of

High-yielding continuous-flow synthesis of antimalarial drug hydroxychloroquine

• Eric Yu,
• Hari P. R. Mangunuru,
• Nakul S. Telang,
• Caleb J. Kong,
• Jenson Verghese,
• Stanley E. Gilliland III,
• Saeed Ahmad,
• Raymond N. Dominey and
• B. Frank Gupton

Beilstein J. Org. Chem. 2018, 14, 583–592, doi:10.3762/bjoc.14.45

• reacted under hydrogen pressure with mechanical stirring. The dip tube in the CSTR was outfitted with a fritted metal filter, allowing for retention of the heterogeneous catalyst within the CSTR vessel. Optimization of this CSTR-based flow process (Table 3) showed near quantitative yields of 12 over a

Ni nanoparticles on RGO as reusable heterogeneous catalyst: effect of Ni particle size and intermediate composite structures in C–S cross-coupling reaction

• Debasish Sengupta,
• Koushik Bhowmik,
• Goutam De and
• Basudeb Basu

Beilstein J. Org. Chem. 2017, 13, 1796–1806, doi:10.3762/bjoc.13.174

• catalytic process has been established for the first time, and found to be best in the C–S cross-coupling reaction for Ni(0) and Ni(II) NPs of the average sizes 11–12 nm and 4 nm, respectively. Keywords: C–S cross-coupling; heterogeneous catalyst; Ni nanoparticle; reduced graphene oxide; thioether

• efficiency. However, post-catalytic investigations of the heterogeneous catalyst reveal that the Ni NPs are considerably converted to Ni(OH)2, (average particle size 4 nm) and remain closely associated with the Ni NPs on the electron-rich RGO surface and exhibit similar catalytic efficiency. Experimental

• , Jadavpur, Kolkata 700032, India. Fax: +91 33 24730957; Tel: +91 33 23223403 10.3762/bjoc.13.174 Abstract The present work demonstrates the C–S cross-coupling reaction between aryl halides and thiols using nickel nanoparticles (Ni NPs) supported on reduced graphene oxide (Ni/RGO) as a heterogeneous

Continuous-flow processes for the catalytic partial hydrogenation reaction of alkynes

• Carmen Moreno-Marrodan,
• Francesca Liguori and
• Pierluigi Barbaro

Beilstein J. Org. Chem. 2017, 13, 734–754, doi:10.3762/bjoc.13.73

• , selective liquid phase flow processes for the fine-chemicals synthesis, including partial hydrogenations, usually requires a more intimate contact with the heterogeneous catalyst to be efficient. One example is the so-called "confinement effect" found in mesoporous catalytic materials [77][78]. Catalytic

Continuous N-alkylation reactions of amino alcohols using γ-Al₂O₃ and supercritical CO₂: unexpected formation of cyclic ureas and urethanes by reaction with CO₂

• Emilia S. Streng,
• Darren S. Lee,
• Michael W. George and
• Martyn Poliakoff

Beilstein J. Org. Chem. 2017, 13, 329–337, doi:10.3762/bjoc.13.36

• 10.3762/bjoc.13.36 Abstract The use of γ-Al2O3 as a heterogeneous catalyst in scCO2 has been successfully applied to the amination of alcohols for the synthesis of N-alkylated heterocycles. The optimal reaction conditions (temperature and substrate flow rate) were determined using an automated self

• heterogeneous catalyst at elevated temperature and/or pressure is employed [20][21][22][23][24][25][26][27][28]. As these reactions are mostly carried out in high pressure systems, they are particularly suitable for the use of supercritical solvents. Supercritical solvents are highly compressed and/or heated

• (Scheme 3b, 380 °C at 1 mL min−1), and no imidazolidinone 16 was detected. Conclusion Using a self-optimising reactor and a simple heterogeneous catalyst, γ-Al2O3, moderate to high yields of several alkylated cyclic amines, formed in a two-step intramolecular cyclisation/N-alkyation reaction, using amino

Silica-supported sulfonic acids as recyclable catalyst for esterification of levulinic acid with stoichiometric amounts of alcohols

• Raimondo Maggi,
• N. Raveendran Shiju,
• Veronica Santacroce,
• Giovanni Maestri,
• Franca Bigi and
• Gadi Rothenberg

Beilstein J. Org. Chem. 2016, 12, 2173–2180, doi:10.3762/bjoc.12.207

• in which a heterogeneous catalyst triggers the selective esterification of levulinic acid with a stoichiometric amount of alcohol. In the last years, many methods have been developed for the transformation of homogeneous catalysts into recyclable heterogeneous ones. To prevent leaching, a common

• ). Acidity has been measured via titration method [35] (0.73 mmol H+/g). Esterification reaction Levulinic acid, pentanol and the heterogeneous catalyst were stirred for 24 hours in a batch reactor under air. The acid/alcohol ratio, the reaction temperature and the amount of the catalyst were modified as

Enantioselective carbenoid insertion into C(sp³)–H bonds

• J. V. Santiago and
• A. H. L. Machado

Beilstein J. Org. Chem. 2016, 12, 882–902, doi:10.3762/bjoc.12.87

• heterogeneous conditions, with laponite as support for the catalyst. The reaction afforded moderate yields, diastereomeric ratio and enantioselectivity under both conditions. The supported catalytic system was reused over three cycles with no performance decrease. The same heterogeneous catalyst was also used

Effective immobilisation of a metathesis catalyst bearing an ammonium-tagged NHC ligand on various solid supports

• Krzysztof Skowerski,
• Jacek Białecki,
• Stefan J. Czarnocki,
• Karolina Żukowska and
• Karol Grela

Beilstein J. Org. Chem. 2016, 12, 5–15, doi:10.3762/bjoc.12.2

• * might serve as in situ heterogeneous catalyst for a tandem olefin metathesis-hydrogenation transformation. To test this possibility we ran CM of 17 and 18 and when the metathesis reaction was complete the resulting product was subjected to reduction by applying hydrogen gas at atmospheric pressure

• on commercially available palladium on carbon (10 wt % Pd/C) [62]. The resulting bimetallic Ru–Pd heterogeneous catalyst 8-Pd/C exhibited the same activity in metathesis as catalyst deposited on activated carbon. Interestingly, the E/Z selectivity in reaction carried out with 8-C* was significantly

Recent advances in copper-catalyzed C–H bond amidation

• Jie-Ping Wan and
• Yanfeng Jing

Beilstein J. Org. Chem. 2015, 11, 2209–2222, doi:10.3762/bjoc.11.240

• catalytic protocol was later developed by Mizuno et al. [74] for the amidation of terminal alkynes using lactam, sulfonamide or cyclic carbamates. The application of Cu(OH)2 as heterogeneous catalyst allowed the synthesis of ynamides 77 with moderate to excellent yield under air (Scheme 20). A latest work

Ru complexes of Hoveyda–Grubbs type immobilized on lamellar zeolites: activity in olefin metathesis reactions

• Hynek Balcar,
• Naděžda Žilková,
• Martin Kubů,
• Michal Mazur,
• Zdeněk Bastl and
• Jiří Čejka

Beilstein J. Org. Chem. 2015, 11, 2087–2096, doi:10.3762/bjoc.11.225

• ] and such zeolites offer the possibility of their modifications with organometallic moieties in a similar way as mesoporous molecular sieves. Limbach et al. [20] used MWW material as a support for Ru heterogeneous catalyst for cyclooctene oligomerization, however, its activity was rather low. In this

Reactions of nitroxides 15. Cinnamates bearing a nitroxyl moiety synthesized using a Mizoroki–Heck cross-coupling reaction

• Jerzy Zakrzewski and
• Bogumiła Huras

Beilstein J. Org. Chem. 2015, 11, 1155–1162, doi:10.3762/bjoc.11.130

• a heterogeneous catalyst which is immobilized on a solid support. In addition to the widely highlighted unquestionable advantages of immobilized, heterogeneous catalysts (easy separation from the reaction mixture and the possibility of re-use), such catalysts are rigidly anchored on a carrier and

Cross-dehydrogenative coupling for the intermolecular C–O bond formation

• Igor B. Krylov,
• Vera A. Vil’ and
• Alexander O. Terent’ev

Beilstein J. Org. Chem. 2015, 11, 92–146, doi:10.3762/bjoc.11.13

Integration of enabling methods for the automated flow preparation of piperazine-2-carboxamide

• Richard J. Ingham,
• Claudio Battilocchio,
• Joel M. Hawkins and
• Steven V. Ley

Beilstein J. Org. Chem. 2014, 10, 641–652, doi:10.3762/bjoc.10.56

• packed beds facilitates recycling of the catalyst, providing a further cost advantage. Interestingly, we have now found that no activation of the zirconia is needed (this is the same as for nitrile hydrations with manganese dioxide, but unlike the use of zirconia as a heterogeneous catalyst for Meerwein

Continuous-flow Heck synthesis of 4-methoxybiphenyl and methyl 4-methoxycinnamate in supercritical carbon dioxide expanded solvent solutions

• Phei Li Lau,
• Ray W. K. Allen and
• Peter Styring

Beilstein J. Org. Chem. 2013, 9, 2886–2897, doi:10.3762/bjoc.9.325

• they are or after some form of regeneration [17]. The types of heterogeneous catalyst can be further categorised by their support, with examples including polymers, dendrimers, mesoporous materials, zeolites, metal oxides, and carbon. Reactions using palladium supported on mesoporous materials have

• stable and highly active heterogeneous catalyst in the Heck reactions of styrene and halides, including iodides, chlorine substituents, and both activated and non-activated bromine [32]. It has been rationalised that the MgLaO support itself appears to act as a base, which in turn acted as an electron

Novel supramolecular affinity materials based on (−)-isosteviol as molecular templates

• Christina Lohoelter,
• Malte Brutschy,
• Daniel Lubczyk and
• Siegfried R. Waldvogel

Beilstein J. Org. Chem. 2013, 9, 2821–2833, doi:10.3762/bjoc.9.317

• all-syn-15 was subsequently cleaved by hydrogenolysis using standard conditions (Scheme 6) [69]. The tricarboxylic acid all-syn-16 was isolated in almost quantitative yield. In this protocol the heterogeneous catalyst did not affect the quinoxaline moieties by over-reduction. With this versatile

Advancements in the mechanistic understanding of the copper-catalyzed azide–alkyne cycloaddition

• Regina Berg and
• Bernd F. Straub

Beilstein J. Org. Chem. 2013, 9, 2715–2750, doi:10.3762/bjoc.9.308

• ligand (1.1 mol %) the test reaction of benzyl azide with phenylacetylene gave 99% yield after one hour in an aqueous medium (DMSO:H2O 1:3) [85]. CuAAC catalysis with molecularly defined copper(I) complexes as (pre-)catalysts Only recently, the potential of copper(I) acetate as heterogeneous catalyst for

• this heterogeneous catalyst in a variety of solvents at room temperature under aerobic conditions. At the beginning of each reaction, the authors observed a bright yellow colour, which might be due to the formation of transient copper(I) acetylide species [126][127]. And indeed did the isolation of

Silica sulfuric acid: a reusable solid catalyst for one pot synthesis of densely substituted pyrrole-fused isocoumarins under solvent-free conditions

• Sudipta Pathak,
• Kamalesh Debnath and
• Animesh Pramanik

Beilstein J. Org. Chem. 2013, 9, 2344–2353, doi:10.3762/bjoc.9.269

• reusable solid supported/heterogeneous catalyst for the efficient synthesis of heterocyclic compounds remains a challenge to chemists in laboratories and in the industry [22][23]. Reactions with reagents that are immobilized on inorganic solid supports show several advantages over the conventional